Lifted Time Stable Inversion Based High Precision Feedforward Control for Non-minimum Phase Systems

Model-based feedforward is essential to realize high-precision tracking in advanced manufacturing. The crucial step is to solve the inverse problem, which has unstable solution for non-minimum phase systems. The existing stable inversion method necessitates fixed initial and final conditions of the tracking task. However, the initial and final conditions are assigned differently according to diverse requirements in practice. This paper proposes a new stable inversion based feedforward control method. By reformulating the tracking problem in lifted time form and truncating the infinite-dimensional inverse operator, the proposed method addresses the inverse problem for stable solution and permits arbitrary initial and final conditions with rigorous stability analysis and robustness analysis. The implementation of the developed method is presented. The high precision tracking performance of the proposed method is illustrated by simulation.